1. Field of the Invention
The present invention relates to an audio device for generating two or more sets of surround signals from 2-channel stereo signals, and a method for generating surround sound.
2. Description of the Related Art
Conventionally, an audio device which generates a surround signal from 2-channel stereo signals has been well known (for example, see Japanese Patent Laid-open No. 2003-333698). In this audio device, input stereo signals INL and INR are passed through an adaptive non-correlator to generate surround signals SL and SR. For example, the adaptive non-correlator is realized in the adaptive signal processing using an FIR filter.
Although the above-mentioned audio device can generate a set of surround signals SL and SR based on 2-channel stereo signals, there have been no specific descriptions for generating two or more sets of surround signals. Even if an approach for generating a surround signal using the adaptive non-correlator is repeated, the same surround signal is generated only. Therefore, although two or more sets of surround signals are generated based on 2-channel stereo signals, spatially broad surround sound cannot be generated for the increased number of speakers. Therefore, it would be necessary to expand channels by adding different processing circuits (for example, a matrix decode circuit), thereby complicating the configuration and process.